Immortal, Immortality - Vine's Expository Dictionary of New Testament Words
Immortal, Immortality[ 1,,G110, athanasia ]
lit., deathlessness" (a, negative, thanatos, "death"), is rendered "immortality" in 1 Corinthians 15:53-54, of the glorified body of the believer; 1 Timothy 6:16, of the nature of God. Moulton and Miligan (Vocab.) show that in early times the word had the wide connotation of freedom from death; they also quote Ramsay (Luke the Physician, p. 273), with reference to the use of the word in sepulchral epitaphs. In a papyrus writing of the sixth century, "a petitioner says that he will send up 'unceasing (athanatous)' hymns to the Lord Christ for the life of the man with whom he is pleading." In the NT, however, athanasia expresses more than deathlessness, it suggests the quality of the life enjoyed, as is clear from 2 Corinthians 5:4; for the believer what is mortal is to be "swallowed up of life."
Note: The adjective aphthartos, translated "immortal" in 1 Timothy 1:17, AV, does not bear that significance, it means "incorruptible." So with the noun aphtharsia, "incorruption," translated "immortality," in the AV of Romans 2:7; 2 Timothy 1:10. See CORRUPT, B, No. 3, and C, No. 2.